This section provides background information related to the present disclosure which is not necessarily prior art.
The edge to edge pseudo wire emulation (PWE3) technology aims to connect the traditional services, such as frame relay, Asynchronous Transfer Mode (ATM), and Ethernet, and to provide service emulation over a packet switching network (PSN), thus realizing the features of the emulated original services as much as possible. The technology ensures the user service quality, and the user does not find any difference of the services. During network construction and transition, the technology provides high quality of interconnection between the user who is using the traditional services and the operator, thus protecting the original investment of the user and the operator.
The link bundling technology is to bundle the physical interfaces, thus realizing low cost and high bandwidth, for example, Ethernet bundling and Packet Over SDH (POS) interface bundling. The link bundling technology usually includes two processes: establishing a bundling interface, and adding a physical interface to the bundling interface as a member interface. The bundling interface has the same physical attributes and three-layer attributes as the independent physical interface. The bundling interface can run the corresponding link layer protocols, such as address resolution protocol (ARP) of the Ethernet, and high-speed data link control (HDLC) of the POS interface. The member interface completes the one-to-one link protocol, and the status of the bundling interface is maintained by the member interface status together.
In the Ethernet, the essence of the PWE3 technology is the point-to-point layer 2 virtual private network (VPN) technology. The link bundling process includes: first establishing point-to-point pseudo wire (PW) between provider edge devices (PEs), and then using label distribution protocol (LDP) or resource reservation protocol (RSVP) to transmit the inner label between the two ends of the PW. The outer label can be IP or label switch path (LSP). The outer label determines the PEs at the two ends of the PW, and the inner label determines the specific PW on the PE. Meanwhile, the physical features of the service are emulated over the forwarding layer, such as the ATM Quality of Server (QoS) and the alarm indication of the synchronous digital hierarchy (SDH). When the message is forwarded, the physical frame is directly encapsulated, such as the cell of the ATM and the Ethernet frame, and the protocol carried by the data frame is ignored, which applies to the point-to-point application.
The current internet engineering task force (IETF) draft has already defined the encapsulation format of the Ethernet, ATM, frame relay, synchronous optical network (SONET), and SDH emulation. But the draft can only apply to the PW establishment on one interface and the message encapsulation.
To implement PWE3 function on a router, the PW needs to be established according to a specific physical interface. The interface bundling technology is a choice for improving the physical bandwidth of the interface. The interface bundling has all the attributes of the physical interface and meanwhile improves the bandwidth. To the POS, the physical layer is the SDH and the link layer encapsulation is the point-to-point protocol (PPP). Because a PWE3 is a point-to-point application, and ignores the link protocol carried by the interface, the link layer needs to run the link aggregation control protocol (LACP) to maintain the member physical interface status for the Ethernet interface bundling on a one-to-one basis. For the member interface requiring one-to-one link negotiation of the bundling interface, the link negotiation message of the member interface is encapsulated by two-layer labels before reaching the remote end PE. Because the inner label of the PE can only distinguish the PW, the inner label cannot distinguish the corresponding member interface. The member interface cannot complete one-to-one link path negotiation across the PSN. Therefore, the bundling interface requiring negotiation between member interfaces cannot provide the PWE3 service.